A person travels for 4 hrs at the speed of 13 km/hr and for 2 hrs at the speed of 14 km/hr. At the end of it, he finds that he has covered 4/5 of the total distance. At what average speed should he travel to cover the whole distance in 8 hrs?

A person travels for 4 hrs at the speed of 13 km/hr and for 2 hrs at the speed of 14 km/hr. At the end of it, he finds that he has covered 4/5 of the total distance. At what average speed should he travel to cover the whole distance in 8 hrs?